X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/52bcc044e3371e9808123356784cf44dd11132dd..f9e4952c0d45a2afdc9267c8cc9500462a82ad11:/entropy.c

diff --git a/entropy.c b/entropy.c
index 15869ea0..431d5ea5 100644
--- a/entropy.c
+++ b/entropy.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000 Damien Miller.  All rights reserved.
+ * Copyright (c) 2001 Damien Miller.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -9,11 +9,6 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by Markus Friedl.
- * 4. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
@@ -29,624 +24,131 @@
 
 #include "includes.h"
 
-#include "ssh.h"
-#include "xmalloc.h"
-
 #include <openssl/rand.h>
-#include <openssl/sha.h>
-
-RCSID("$Id$");
-
-#ifdef EGD_SOCKET
-#ifndef offsetof
-# define offsetof(type, member) ((size_t) &((type *)0)->member)
-#endif
-/* Collect entropy from EGD */
-void get_random_bytes(unsigned char *buf, int len)
-{
-	static int egd_socket = -1;
-	int c;
-	char egd_message[2] = { 0x02, 0x00 };
-	struct sockaddr_un addr;
-	int addr_len;
-
-	memset(&addr, '\0', sizeof(addr));
-	addr.sun_family = AF_UNIX;
-	
-	/* FIXME: compile time check? */
-	if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path))
-		fatal("Random pool path is too long");
-	
-	strcpy(addr.sun_path, EGD_SOCKET);
-	
-	addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET);
-	
-	if (egd_socket == -1) {
-		egd_socket = socket(AF_UNIX, SOCK_STREAM, 0);
-		if (egd_socket == -1)
-			fatal("Couldn't create AF_UNIX socket: %s", strerror(errno));
-		if (connect(egd_socket, (struct sockaddr*)&addr, addr_len) == -1)
-			fatal("Couldn't connect to EGD socket \"%s\": %s", addr.sun_path, strerror(errno));
-	}	
-
-	if (len > 255)
-		fatal("Too many bytes to read from EGD");
-	
-	/* Send blocking read request to EGD */
-	egd_message[1] = len;
+#include <openssl/crypto.h>
 
-	c = atomicio(write, egd_socket, egd_message, sizeof(egd_message));
-	if (c == -1)
-		fatal("Couldn't write to EGD socket \"%s\": %s", EGD_SOCKET, strerror(errno));
-
-	c = atomicio(read, egd_socket, buf, len);
-	if (c <= 0)
-		fatal("Couldn't read from EGD socket \"%s\": %s", EGD_SOCKET, strerror(errno));
-	
-	close(EGD_SOCKET);
-}
-#else /* !EGD_SOCKET */
-#ifdef RANDOM_POOL
-/* Collect entropy from /dev/urandom or pipe */
-void get_random_bytes(unsigned char *buf, int len)
-{
-	static int random_pool = -1;
-	int c;
-
-	if (random_pool == -1) {
-		random_pool = open(RANDOM_POOL, O_RDONLY);
-		if (random_pool == -1)
-			fatal("Couldn't open random pool \"%s\": %s", RANDOM_POOL, strerror(errno));
-	}
-	
-	c = atomicio(read, random_pool, buf, len);
-	if (c <= 0)
-		fatal("Couldn't read from random pool \"%s\": %s", RANDOM_POOL, strerror(errno));
-}
-#endif /* RANDOM_POOL */
-#endif /* EGD_SOCKET */
+#include "ssh.h"
+#include "misc.h"
+#include "xmalloc.h"
+#include "atomicio.h"
+#include "pathnames.h"
+#include "log.h"
 
-#if !defined(EGD_SOCKET) && !defined(RANDOM_POOL)
-/* 
- * FIXME: proper entropy estimations. All current values are guesses
- * FIXME: (ATL) do estimates at compile time?
- * FIXME: More entropy sources
- * FIXME: (ATL) bring in entropy sources from file
- * FIXME: (ATL) add heuristic to increase the timeout if needed
+/*
+ * Portable OpenSSH PRNG seeding:
+ * If OpenSSL has not "internally seeded" itself (e.g. pulled data from
+ * /dev/random), then we execute a "ssh-rand-helper" program which
+ * collects entropy and writes it to stdout. The child program must
+ * write at least RANDOM_SEED_SIZE bytes. The child is run with stderr
+ * attached, so error/debugging output should be visible.
+ *
+ * XXX: we should tell the child how many bytes we need.
  */
 
-/* slow command timeouts (all in milliseconds) */
-/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
-static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
-
-static int prng_seed_loaded = 0;
-static int prng_seed_saved = 0;		
-
-typedef struct
-{
-	/* Proportion of data that is entropy */
-	double rate;
-	/* Counter goes positive if this command times out */
-	unsigned int badness;
-	/* Increases by factor of two each timeout */
-	unsigned int sticky_badness;
-	/* Path to executable */
-	const char *path;
-	/* argv to pass to executable */
-	const char *args[5];
-} entropy_source_t;
-
-double stir_from_system(void);
-double stir_from_programs(void);
-double stir_gettimeofday(double entropy_estimate);
-double stir_clock(double entropy_estimate);
-double stir_rusage(int who, double entropy_estimate);
-double hash_output_from_command(entropy_source_t *src, char *hash);
-
-entropy_source_t entropy_sources[] = {
-#ifdef PROG_LS
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/log", NULL } },
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/adm", NULL } },
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/mail", NULL } },
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/var/spool/mail", NULL } },
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/proc", NULL } },
-	{ 0.002, 0, 1, PROG_LS,       { "ls", "-alni", "/tmp", NULL } },
-#endif
-#ifdef PROG_NETSTAT
-	{ 0.005, 0, 1, PROG_NETSTAT,  { "netstat","-an", NULL, NULL } },
-	{ 0.010, 0, 1, PROG_NETSTAT,  { "netstat","-in", NULL, NULL } },
-	{ 0.002, 0, 1, PROG_NETSTAT,  { "netstat","-rn", NULL, NULL } },
-	{ 0.002, 0, 1, PROG_NETSTAT,  { "netstat","-s", NULL, NULL } },
-#endif
-#ifdef PROG_ARP
-	{ 0.002, 0, 1, PROG_ARP,      { "arp","-a","-n", NULL } },
-#endif
-#ifdef PROG_IFCONFIG
-	{ 0.002, 0, 1, PROG_IFCONFIG, { "ifconfig", "-a", NULL, NULL } },
-#endif
-#ifdef PROG_PS
-	{ 0.003, 0, 1, PROG_PS,       { "ps", "laxww", NULL, NULL } },
-	{ 0.003, 0, 1, PROG_PS,       { "ps", "-al", NULL, NULL } },
-	{ 0.003, 0, 1, PROG_PS,       { "ps", "-efl", NULL, NULL } },
-#endif
-#ifdef PROG_W
-	{ 0.005, 0, 1, PROG_W,        { "w", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_WHO
-	{ 0.001, 0, 1, PROG_WHO,      { "who","-i", NULL, NULL } },
-#endif
-#ifdef PROG_LAST
-	{ 0.001, 0, 1, PROG_LAST,     { "last", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_LASTLOG
-	{ 0.001, 0, 1, PROG_LASTLOG,  { "lastlog", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_DF
-	{ 0.010, 0, 1, PROG_DF,       { "df", NULL, NULL, NULL } },
-	{ 0.010, 0, 1, PROG_DF,       { "df", "-i", NULL, NULL } },
-#endif
-#ifdef PROG_VMSTAT
-	{ 0.010, 0, 1, PROG_VMSTAT,   { "vmstat", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_UPTIME
-	{ 0.001, 0, 1, PROG_UPTIME,   { "uptime", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_IPCS
-	{ 0.001, 0, 1, PROG_IPCS,     { "-a", NULL, NULL, NULL } },
-#endif
-#ifdef PROG_TAIL
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/messages", NULL, NULL } },
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/syslog", NULL, NULL } },
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/messages", NULL, NULL } },
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/syslog", NULL, NULL } },
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/log/maillog", NULL, NULL } },
-	{ 0.001, 0, 1, PROG_TAIL,     { "tail", "-200", "/var/adm/maillog", NULL, NULL } },
-#endif
-	{ 0.000, 0, 0, NULL,          { NULL, NULL, NULL, NULL, NULL } },
-};
-
-double 
-stir_from_system(void)
-{
-	double total_entropy_estimate;
-	long int i;
-	
-	total_entropy_estimate = 0;
-	
-	i = getpid();
-	RAND_add(&i, sizeof(i), 0.1);
-	total_entropy_estimate += 0.1;
-	
-	i = getppid();
-	RAND_add(&i, sizeof(i), 0.1);
-	total_entropy_estimate += 0.1;
-
-	i = getuid();
-	RAND_add(&i, sizeof(i), 0.0);
-	i = getgid();
-	RAND_add(&i, sizeof(i), 0.0);
-
-	total_entropy_estimate += stir_gettimeofday(1.0);
-	total_entropy_estimate += stir_clock(0.2);
-	total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
-
-	return(total_entropy_estimate);
-}
-
-double 
-stir_from_programs(void)
-{
-	int i;
-	int c;
-	double entropy_estimate;
-	double total_entropy_estimate;
-	char hash[SHA_DIGEST_LENGTH];
-
-	/*
-	 * Run through list of programs twice to catch differences
-	 */
-	total_entropy_estimate = 0;
-	for(i = 0; i < 2; i++) {
-		c = 0;
-		while (entropy_sources[c].path != NULL) {
-
-			if (!entropy_sources[c].badness) {
-				/* Hash output from command */
-				entropy_estimate = hash_output_from_command(&entropy_sources[c], hash);
-
-				/* Scale back entropy estimate according to command's rate */
-				entropy_estimate *= entropy_sources[c].rate;
- 
-				/* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */
-				if (entropy_estimate > SHA_DIGEST_LENGTH)
-					entropy_estimate = SHA_DIGEST_LENGTH;
-
- 			/* * Scale back estimates for subsequent passes through list */
-				entropy_estimate /= 10.0 * (i + 1.0);
-			
-				/* Stir it in */
-				RAND_add(hash, sizeof(hash), entropy_estimate);
-
-/* FIXME: turn this off later */
-#if 1
-				debug("Got %0.2f bytes of entropy from %s", entropy_estimate, 
-					entropy_sources[c].path);
-#endif
-
-				total_entropy_estimate += entropy_estimate;
+RCSID("$Id$");
 
-			/* Execution times should be a little unpredictable */
-				total_entropy_estimate += stir_gettimeofday(0.05);
-				total_entropy_estimate += stir_clock(0.05);
-				total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1);
-				total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1);
-			} else {
-/* FIXME: turn this off later */
-#if 1
-				debug("Command '%s %s %s' disabled (badness %d)",
-					entropy_sources[c].path, entropy_sources[c].args[1],
-					entropy_sources[c].args[2], entropy_sources[c].badness);
+#ifndef OPENSSL_PRNG_ONLY
+#define RANDOM_SEED_SIZE 48
+static uid_t original_uid, original_euid;
 #endif
 
-				if (entropy_sources[c].badness > 0)
-					entropy_sources[c].badness--;
-			}
-
-			c++;
-		}
-	}
-	
-	return(total_entropy_estimate);
-}
-
-double
-stir_gettimeofday(double entropy_estimate)
-{
-	struct timeval tv;
-	
-	if (gettimeofday(&tv, NULL) == -1)
-		fatal("Couldn't gettimeofday: %s", strerror(errno));
-
-	RAND_add(&tv, sizeof(tv), entropy_estimate);
-	
-	return(entropy_estimate);
-}
-
-double
-stir_clock(double entropy_estimate)
-{
-#ifdef HAVE_CLOCK
-	clock_t c;
-	
-	c = clock();
-	RAND_add(&c, sizeof(c), entropy_estimate);
-	
-	return(entropy_estimate);
-#else /* _HAVE_CLOCK */
-	return(0);
-#endif /* _HAVE_CLOCK */
-}
-
-double
-stir_rusage(int who, double entropy_estimate)
-{
-#ifdef HAVE_GETRUSAGE
-	struct rusage ru;
-	
-	if (getrusage(who, &ru) == -1)
-		fatal("Couldn't getrusage: %s", strerror(errno));
-
-	RAND_add(&ru, sizeof(ru), 0.1);
-
-	return(entropy_estimate);
-#else /* _HAVE_GETRUSAGE */
-	return(0);
-#endif /* _HAVE_GETRUSAGE */
-}
-
-double
-hash_output_from_command(entropy_source_t *src, char *hash)
+void
+seed_rng(void)
 {
-	static int devnull = -1;
+#ifndef OPENSSL_PRNG_ONLY
+	int devnull;
 	int p[2];
-	fd_set rdset;
-	int cmd_eof = 0, error_abort = 0;
 	pid_t pid;
-	int status;
-	char buf[2048];
-	int bytes_read;
-	int total_bytes_read;
-	SHA_CTX sha;
-	
-	if (devnull == -1) {
-		devnull = open("/dev/null", O_RDWR);
-		if (devnull == -1)
-			fatal("Couldn't open /dev/null: %s", strerror(errno));
-	}
-	
-	if (pipe(p) == -1)
-		fatal("Couldn't open pipe: %s", strerror(errno));
-
-	switch (pid = fork()) {
-		case -1: /* Error */
-			close(p[0]);
-			close(p[1]);
-			fatal("Couldn't fork: %s", strerror(errno));
-			/* NOTREACHED */
-		case 0: /* Child */
-			dup2(devnull, STDIN_FILENO);
-			dup2(p[1], STDOUT_FILENO);
-			dup2(p[1], STDERR_FILENO);
-			close(p[0]);
-			close(p[1]);
-			close(devnull);
-
-			execv(src->path, (char**)(src->args));
-			debug("(child) Couldn't exec '%s %s %s': %s", src->path,
-				src->args[1], src->args[2], strerror(errno));
-			src->badness = src->sticky_badness = 128;
-			_exit(-1);
-		default: /* Parent */
-			break;
-	}
-
-	RAND_add(&pid, sizeof(&pid), 0.0);
-
-	close(p[1]);
-
-	/* Hash output from child */
-	SHA1_Init(&sha);
-	total_bytes_read = 0;
-
-	while (!error_abort && !cmd_eof) {
-		int ret;
-		struct timeval tv;
-
-		FD_ZERO(&rdset);
-		FD_SET(p[0], &rdset);
-		tv.tv_sec = entropy_timeout_current / 1000;
-		tv.tv_usec = (entropy_timeout_current % 1000) * 1000;
-
-		ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
-		switch (ret) {
-		case 0:
-			/* timer expired */
-			error_abort = 1;
-			break;
-			
-		case 1:
-			/* command input */
-			bytes_read = read(p[0], buf, sizeof(buf));
-			if (bytes_read == -1) {
-				error_abort = 1;
-				break;
-			}
-			SHA1_Update(&sha, buf, bytes_read);
-			total_bytes_read += bytes_read;
-			RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
-			cmd_eof = bytes_read ? 0 : 1;
-
-			break;
-
-		case -1:
-		default:
-			error("Command '%s %s': select() failed: %s", src->path, src->args[1],
-				strerror(errno));
-			error_abort = 1;
-			break;
-		} /* switch ret */
-
-		RAND_add(&tv, sizeof(&tv), 0.0);
-	} /* while !error_abort && !cmd_eof */
-
-	SHA1_Final(hash, &sha);
+	int ret;
+	unsigned char buf[RANDOM_SEED_SIZE];
+	mysig_t old_sigchld;
 
-	close(p[0]);
-	
-	if (waitpid(pid, &status, 0) == -1) {
-		error("Couldn't wait for child '%s %s' completion: %s", src->path,
-			src->args[1], strerror(errno));
-		/* return(-1); */ /* FIXME: (ATL) this doesn't feel right */
-		return(0.0);
+	if (RAND_status() == 1) {
+		debug3("RNG is ready, skipping seeding");
+		return;
 	}
 
-	RAND_add(&status, sizeof(&status), 0.0);
+	debug3("Seeding PRNG from %s", SSH_RAND_HELPER);
 
-	if (error_abort) {
-		/* closing p[0] on timeout causes the entropy command to
-		 * SIGPIPE. Take whatever output we got, and mark this command
-		 * as slow */
-		debug("Command %s %s timed out", src->path, src->args[1]);
-		src->sticky_badness *= 2;
-		src->badness = src->sticky_badness;
-		return(total_bytes_read);
-	}
-
-	if (WIFEXITED(status)) {
-		if (WEXITSTATUS(status)==0) {
-			return(total_bytes_read);
-		} else {
-			debug("Exit status was %d", WEXITSTATUS(status));
-			src->badness = src->sticky_badness = 128;
-			return (0.0);
+	if ((devnull = open("/dev/null", O_RDWR)) == -1)
+		fatal("Couldn't open /dev/null: %s", strerror(errno));
+	if (pipe(p) == -1)
+		fatal("pipe: %s", strerror(errno));
+
+	old_sigchld = signal(SIGCHLD, SIG_DFL);
+	if ((pid = fork()) == -1)
+		fatal("Couldn't fork: %s", strerror(errno));
+	if (pid == 0) {
+		dup2(devnull, STDIN_FILENO);
+		dup2(p[1], STDOUT_FILENO);
+		/* Keep stderr open for errors */
+		close(p[0]);
+		close(p[1]);
+		close(devnull);
+
+		if (original_uid != original_euid &&
+		    ( seteuid(getuid()) == -1 ||
+		      setuid(original_uid) == -1) ) {
+			fprintf(stderr, "(rand child) setuid(%li): %s\n",
+			    (long int)original_uid, strerror(errno));
+			_exit(1);
 		}
-	} else if (WIFSIGNALED(status)) {
-		debug("Returned on uncaught signal %d !", status);
-		src->badness = src->sticky_badness = 128;
-		return(0.0);
-	} else
-		return(0.0);
-}
-
-/*
- * prng seedfile functions
- */
-int
-prng_check_seedfile(char *filename) {
 
-	struct stat st;
-
-	/* FIXME raceable: eg replace seed between this stat and subsequent open */
-	/* Not such a problem because we don't trust the seed file anyway */
-	if (lstat(filename, &st) == -1) {
-		/* Fail on hard errors */
-		if (errno != ENOENT)
-			fatal("Couldn't stat random seed file \"%s\": %s", filename,
-				strerror(errno));
-
-		return(0);
+		execl(SSH_RAND_HELPER, "ssh-rand-helper", NULL);
+		fprintf(stderr, "(rand child) Couldn't exec '%s': %s\n",
+		    SSH_RAND_HELPER, strerror(errno));
+		_exit(1);
 	}
 
-	/* regular file? */
-	if (!S_ISREG(st.st_mode))
-		fatal("PRNG seedfile %.100s is not a regular file", filename);
-
-	/* mode 0600, owned by root or the current user? */
-	if (((st.st_mode & 0177) != 0) || !(st.st_uid == geteuid()))
-		fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d",
-			 filename, getuid());
-
-	return(1);
-}
-
-void
-prng_write_seedfile(void) {
-	int fd;
-	char seed[1024];
-	char filename[1024];
-	struct passwd *pw;
-
-	/* Don't bother if we have already saved a seed */
-	if (prng_seed_saved)
-		return;
-	
-	prng_seed_saved = 1;
-	
-	pw = getpwuid(getuid());
-	if (pw == NULL)
-		fatal("Couldn't get password entry for current user (%i): %s", 
-			getuid(), strerror(errno));
-				
-	/* Try to ensure that the parent directory is there */
-	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
-		SSH_USER_DIR);
-	mkdir(filename, 0700);
-
-	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
-		SSH_PRNG_SEED_FILE);
-
-	debug("writing PRNG seed to file %.100s", filename);
-
-	RAND_bytes(seed, sizeof(seed));
-
-	/* Don't care if the seed doesn't exist */
-	prng_check_seedfile(filename);
-	
-	if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1)
-		fatal("couldn't access PRNG seedfile %.100s (%.100s)", filename, 
-			strerror(errno));
-	
-	if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed))
-		fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, 
-			 strerror(errno));
-
-	close(fd);
-}
-
-void
-prng_read_seedfile(void) {
-	int fd;
-	char seed[1024];
-	char filename[1024];
-	struct passwd *pw;
-	
-	pw = getpwuid(getuid());
-	if (pw == NULL)
-		fatal("Couldn't get password entry for current user (%i): %s", 
-			getuid(), strerror(errno));
-			
-	snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, 
-		SSH_PRNG_SEED_FILE);
-
-	debug("loading PRNG seed from file %.100s", filename);
-
-	if (!prng_check_seedfile(filename)) {
-		verbose("Random seed file not found, creating new");
-		prng_write_seedfile();
-		
-		/* Reseed immediatly */
-		(void)stir_from_system();
-		(void)stir_from_programs();
-		return;
-	}
-
-	/* open the file and read in the seed */
-	fd = open(filename, O_RDONLY);
-	if (fd == -1)
-		fatal("could not open PRNG seedfile %.100s (%.100s)", filename, 
-			strerror(errno));
+	close(devnull);
+	close(p[1]);
 
-	if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) {
-		verbose("invalid or short read from PRNG seedfile %.100s - ignoring",
-			filename);
-		memset(seed, '\0', sizeof(seed));
-	}
-	close(fd);
+	memset(buf, '\0', sizeof(buf));
+	ret = atomicio(read, p[0], buf, sizeof(buf));
+	if (ret == -1)
+		fatal("Couldn't read from ssh-rand-helper: %s",
+		    strerror(errno));
+	if (ret != sizeof(buf))
+		fatal("ssh-rand-helper child produced insufficient data");
 
-	/* stir in the seed, with estimated entropy zero */
-	RAND_add(&seed, sizeof(seed), 0.0);
-}
+	close(p[0]);
 
-#endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
+	if (waitpid(pid, &ret, 0) == -1)
+	       fatal("Couldn't wait for ssh-rand-helper completion: %s",
+		   strerror(errno));
+	signal(SIGCHLD, old_sigchld);
 
-#if defined(EGD_SOCKET) || defined(RANDOM_POOL)
+	/* We don't mind if the child exits upon a SIGPIPE */
+	if (!WIFEXITED(ret) &&
+	    (!WIFSIGNALED(ret) || WTERMSIG(ret) != SIGPIPE))
+		fatal("ssh-rand-helper terminated abnormally");
+	if (WEXITSTATUS(ret) != 0)
+		fatal("ssh-rand-helper exit with exit status %d", ret);
 
-/*
- * Seed OpenSSL's random number pool from Kernel random number generator
- * or EGD
- */
-void
-seed_rng(void)
-{
-	char buf[32];
-	
-	debug("Seeding random number generator");
-	get_random_bytes(buf, sizeof(buf));
 	RAND_add(buf, sizeof(buf), sizeof(buf));
 	memset(buf, '\0', sizeof(buf));
-}
-
-#else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
 
-/*
- * Write a keyfile at exit
- */ 
-void
-prng_seed_cleanup(void *junk)
-{
-	prng_write_seedfile();
+#endif /* OPENSSL_PRNG_ONLY */
+	if (RAND_status() != 1)
+		fatal("PRNG is not seeded");
 }
 
-/*
- * Conditionally Seed OpenSSL's random number pool from
- * syscalls and program output
- */
 void
-seed_rng(void)
+init_rng(void)
 {
-	debug("Seeding random number generator.");
-	debug("OpenSSL random status is now %i\n", RAND_status());
-	debug("%i bytes from system calls", (int)stir_from_system());
-	debug("%i bytes from programs", (int)stir_from_programs());
-	debug("OpenSSL random status is now %i\n", RAND_status());
+	/*
+	 * OpenSSL version numbers: MNNFFPPS: major minor fix patch status
+	 * We match major, minor, fix and status (not patch)
+	 */
+	if ((SSLeay() ^ OPENSSL_VERSION_NUMBER) & ~0xff0L)
+		fatal("OpenSSL version mismatch. Built against %lx, you "
+		    "have %lx", OPENSSL_VERSION_NUMBER, SSLeay());
 
-	if (!prng_seed_loaded)
-	{
-		prng_seed_loaded = 1;
-		prng_seed_saved = 0;		
-		prng_read_seedfile();
-		fatal_add_cleanup(prng_seed_cleanup, NULL);
-		atexit(prng_write_seedfile);
-	}
+#ifndef OPENSSL_PRNG_ONLY
+	if ((original_uid = getuid()) == -1)
+		fatal("getuid: %s", strerror(errno));
+	if ((original_euid = geteuid()) == -1)
+		fatal("geteuid: %s", strerror(errno));
+#endif
 }
-#endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
+